The present invention relates to vehicle seat fittings of the type disclosed in my prior U.S. Pat. No. 3,999,247 and more particularly to such fittings manufactured in a manner which will assure effective irreversible locking engagement of the respective pivotally connected hinge elements in any adjusted position throughout the entire range of adjustment and tolerance extremities of the individual elements in assembled relation without resort to a positive stop for the locking cam and without any possibility of looseness between the interposed elements in the locked position, either as initially adjusted or under conditions of vibration and/or backrest loading in either direction; also which will permit the locking cam to be manually retracted easily for seat back adjustment.
The interengaging teeth of the respective sector and pawl elements employed to arrest relative movement between the seat and its backrest with the fitting installed include tooth angles producing a disengaging force on the pawl in response to pressure on the backrest in either direction and life tests for the fitting required by manufacturers for acceptance include dynamic reverse loading for many thousands of cycles which will effectively destroy the fitting if any looseness between the elements prevails; or may gradually produce an unacceptable disengagement if the moment of the disengaging forces effective on the cam are greater than the frictional resistance forces for retaining the cam against disengagement.